/*
 * JEF - Copyright 2009-2010 Jiyi (mr.jiyi@gmail.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package jef.database.jsqlparser.parser;

/**
 * Describes the input token stream.
 */
public class Token implements java.io.Serializable {

    /**
   * The version identifier for this Serializable class.
   * Increment only if the <i>serialized</i> form of the
   * class changes.
   */
    private static final long serialVersionUID = 1L;

    /**
   * An integer that describes the kind of this token.  This numbering
   * system is determined by JavaCCParser, and a table of these numbers is
   * stored in the file ...Constants.java.
   */
    public int kind;

    /** The line number of the first character of this Token. */
    public int beginLine;

    /** The column number of the first character of this Token. */
    public int beginColumn;

    /** The line number of the last character of this Token. */
    public int endLine;

    /** The column number of the last character of this Token. */
    public int endColumn;

    /**
   * The string image of the token.
   */
    public String image;

    /**
   * A reference to the next regular (non-special) token from the input
   * stream.  If this is the last token from the input stream, or if the
   * token manager has not read tokens beyond this one, this field is
   * set to null.  This is true only if this token is also a regular
   * token.  Otherwise, see below for a description of the contents of
   * this field.
   */
    public Token next;

    /**
   * This field is used to access special tokens that occur prior to this
   * token, but after the immediately preceding regular (non-special) token.
   * If there are no such special tokens, this field is set to null.
   * When there are more than one such special token, this field refers
   * to the last of these special tokens, which in turn refers to the next
   * previous special token through its specialToken field, and so on
   * until the first special token (whose specialToken field is null).
   * The next fields of special tokens refer to other special tokens that
   * immediately follow it (without an intervening regular token).  If there
   * is no such token, this field is null.
   */
    public Token specialToken;

    /**
   * An optional attribute value of the Token.
   * Tokens which are not used as syntactic sugar will often contain
   * meaningful values that will be used later on by the compiler or
   * interpreter. This attribute value is often different from the image.
   * Any subclass of Token that actually wants to return a non-null value can
   * override this method as appropriate.
   */
    public Object getValue() {
        return null;
    }

    /**
   * No-argument constructor
   */
    public Token() {
    }

    /**
   * Constructs a new token for the specified Image.
   */
    public Token(int kind) {
        this(kind, null);
    }

    /**
   * Constructs a new token for the specified Image and Kind.
   */
    public Token(int kind, String image) {
        this.kind = kind;
        this.image = image;
    }

    /**
   * Returns the image.
   */
    public String toString() {
        return image;
    }

    /**
   * Returns a new Token object, by default. However, if you want, you
   * can create and return subclass objects based on the value of ofKind.
   * Simply add the cases to the switch for all those special cases.
   * For example, if you have a subclass of Token called IDToken that
   * you want to create if ofKind is ID, simply add something like :
   *
   *    case MyParserConstants.ID : return new IDToken(ofKind, image);
   *
   * to the following switch statement. Then you can cast matchedToken
   * variable to the appropriate type and use sit in your lexical actions.
   */
    public static Token newToken(int ofKind, String image) {
        switch(ofKind) {
            default:
                return new Token(ofKind, image);
        }
    }

    public static Token newToken(int ofKind) {
        return newToken(ofKind, null);
    }
}
